The present invention relates to an optical control panel system which communicates by means of light to an electro-mechanical control system which, in turn, couples to various sensors and loads. The loads may, for example, be motors that perform various functions and the sensors may be plant system monitors for monitoring various facets of a process.
Conventional control panels utilize switches, annunciators and indicator lights which are operated electrically. Such control panels, as a consequence, require numerous wires and connectors to bring electrical current to the various lights and switches on the panel. Failures on the panel can, therefore, arise as a result of burnt out indicator lights or annunciator lights, faulty switches, shorts or bad connections in the wiring. Moreover, cross talk and other interference problems also occur. Finally, it is necessary to couple the various lights, switches and annunciators to the various electro-mechanical elements which interface to the sensors and lodes. Often the various logic circuits, relays, etc. are located in locations remote from the control panel as a result of which electrical current has to travel relatively large distances. The task of simply connecting wires to all of the logic circuits, and electro-mechanical elements and at the same time avoiding the possibility of arcing or short circuits is a major problem. Consequently, there is a need for a control panel which eliminates the requirement of electrically operated lights and switches.
U.S. Pat. No. 5,090,791 issued Feb. 25, 1992 to Kidder et al. discloses a self-illuminated fibre optic switch which, through mechanical actuation, switches light from an input path to one or more output paths. At the same time there is also disclosed the use of a separate illumination light source to illuminate separate portions of a cap to indicate whether or not the switch is "on" or "off". U.S. Pat. No. 5,046,806 issued Sep. 10, 1991 to Kidder et al. discloses the use of a single fibre control switch in which an illumination source generates light which is directed along an optical fibre to an actuator or switch. Depending on the switch position light is returned back along the same fibre and passes on to a pair of detectors which, from the colour of the light received, can detect the state of the actuator. Although such fully optical switches are now known, realization of such switches to create a fully optical control panel is not known. U.S. Pat. No. 3,999,074 issued to Callaghan discloses a single fibre loop in an optical shutter which interrupts the light path as a means of control. The Callaghan system, however, is not able to discriminate between an "off" control state and an optical system failure which results in no return light.
Accordingly, it is an object of the invention to provide a fully optical control panel. It is a further object of the invention to provide such a control panel in which an optical system failure is readily detectable.